60 A BOOK OF INSECTS 



in any other insects, while " locomotor abdominal ap- 

 pendages " are often present in the adult. The order 

 comprises two sub-orders, viz. : — 



Sub-Order 1. — Thysanura. 



These are the lowliest of all living insects. They are 

 known popularly as " bristle-tails," on account of the long 

 styles, or cerci, which often project from the hinder end 

 of the body ; also as " fish insects," because many of 

 them are clothed with shining scales very similar in 

 appearance to those on the skin of fishes. One small, 

 nearly white species, called Campodea staphylinus, is 

 common in garden mould and under dead leaves. Better 

 known, however, is Lepisma saccharina, the " silver-fish," 

 or " silver-lady " of our cupboards and pantries. It feeds 

 upon a great variety of substances, and sometimes does 

 mischief to old prints, books, &c, by gnawing away the 

 surface of the paper. An allied species is TJtermobia 

 fumorum, which frequents London warehouses and 

 bakeries, Avhere it is termed the " fire brat." Other species 

 are found on the sea shore. In all Thysanura there are 

 ten abdominal segments, some of which carry pairs of 

 rudimentary " limbs." 



Sub-Order 2. — Collembola. 



These are the " spring-tails," so-called because many 

 of the species have a curious leaping apparatus attached 

 to the under surface of the abdomen. This is a kind of 

 two-pronged fork by means of which the insect can hurl 

 itself into the air. Spring-tails may be found among 

 decaying vegetable matter, under bark, and on the surface 

 of stagnant water. According to Mr. C. O. Waterhouse, 

 " one small, white species (Isotoma fimetaria) can live 

 equally well on land and on the top of water ; and as it 



